What's the hardware and firmware version of your router? I don't have this kind of issue. Perhaps you can contact Apple to get some advice, maybe some settings required on the router?

good sharing

As you said you can get internet from TC7650 directly so I am considering the settings on the router. You can reboot both the TC7650 and your router and after total reboot, hook them back together by...

You can reset the router one more time and try http://192.168.0.254

Which firmware you downloaded? Looks like you have US version so I guess you can check if you download the right version or not and unzip the file and upload the bin file

You can email TP-Link support for help. Launch the Deco app, tap the " 三" icon at the upper left corner, tap Help -> Email Us